RU2095865C1 - Method for manufacturing spent fuel transportation and/or storage container - Google Patents

Abstract

FIELD: handling spent nuclear fuel. SUBSTANCE: method includes concreting of cavity between metal internal and external cylindrical metal shells with bottoms and concurrent concreting of specimen cavity identical to container sector. Both cavities are concreted under same conditions. Upon concreting, specimen shells are separated and quality of concrete filler through container height as well as its physical and mechanical properties are estimated by specimen condition. EFFECT: facilitated procedure: improved quality of container. 2 cl, 2 dwg

Description

 The invention relates to containers for long-term dry storage of spent nuclear fuel (SNF) of nuclear power plants in the form of fuel assemblies, in particular to methods for manufacturing containers using concrete as a filler between metal cylindrical shells.

 In the manufacture of building structures, the quality control of derivative processes is carried out according to a previously developed "Map of operational quality control", which is compiled for each structure or structure (Khayutin Yu.G. Monolithic concrete: (Production technology). - M. Stroyizdat, 1981).

The mentioned card includes:
conformity control of physical and mechanical properties of materials, aggregates, etc.

verification of structural readiness and acceptance of concrete;
control of the duration of movement and transportation of concrete mix;
control of workability of concrete mixture and its temperature;
control of the hardening regime in the structure and strength gain.

 Various methods are known for controlling the quality of concrete structures, which make it possible to assess the compliance of their actual characteristics with the specified requirements (see ibid., P. 329,400).

 As for the strength of concrete, it is usually checked by compression testing of control cubes. In addition, for assessing the actual strength, core sampling directly from the body of the concrete structure is practiced, which is unacceptable for the construction of a metal-concrete container for spent nuclear fuel.

 Non-destructive testing methods are usually used to assess the quality of the finished structure, for example, transmission by ionizing radiation, acoustic methods, ultrasonic pulsed methods. However, these methods do not allow to determine the distribution of concrete density over the thickness of the concrete mass and the actual strength of concrete in various areas of the real structure.

A known method of manufacturing concrete containers for SNF, which is carried out in the manufacture of the container according to the patent NRG N 3321250, IPC ⁴ G 21 F 5/00, 1984, the Method includes concreting the tank in the form of a glass.

 The disadvantage of this method is that it does not imply the possibility of determining the distribution of concrete density along the thickness and height of the concrete mass and the possibility of determining the actual strength of concrete in various areas of the container.

The closest in combination of essential features with the invention is the method that is used in the manufacture of a container for storing radioactive waste according to the application EPO N 0264521, IPC ⁴ G 21 F 1/04, 5/00, 19885, which was chosen as the closest analogue prototype. The known method includes concreting the cavity between the metal outer and inner shells with bottoms.

 The disadvantage of this method of manufacturing a container is that it does not imply the possibility of obtaining confirmation of the physicomechanical properties of concrete aggregate anywhere along the height of the container without violating the integrity of the metal shells. In addition, reliable information about the quality of the concrete filling of the cavity of the metal-concrete container and its strength are not provided.

 The objective of the invention is to increase the reliability of information about the quality of the concrete filling of the container and the possibility of confirming the physicomechanical properties of the concrete aggregate anywhere along the height of the container.

 This problem is solved due to the fact that in the known method of manufacturing a container for transporting and / or storing spent nuclear fuel, comprising concreting a cavity between metal outer and inner cylindrical shells with bottoms, according to the invention, concreting a cavity of a sample identical to the sector of said container. At the same time, the concrete mixture is compacted in both of these cavities in the same mode. After concreting, the connector of the sample shells is carried out and the quality of the concrete filling is evaluated according to the height of the container and the physical and mechanical properties of the latter are evaluated.

 When concreting the cavities of the container and the sample, the concrete mixture is supplied from a common switchgear.

 In FIG. 1 shows a diagram of the supply of concrete mix in the cavity of the container and the sample sector; in FIG. 2 view of the bottoms of the outer shells of the container body and the sample sector.

 Technology method for manufacturing a container for SNF is as follows. The metal structure of the container body 1 is installed vertically upside down on the technological supports 2 between the service posts 3. In an embodiment of the invention, the container body is made in the form of a double-walled tank 4 containing the outer and inner metal cylindrical shells with bottoms. The cavity between the shells is covered by a metal base 5, in which slots are provided for installing covers that cover the internal cavity of the container (not shown in the drawing). In the cavity between the shells there is a metal frame 6 made of round reinforcement of a periodic profile. Openings "a" are made in the bottom of the outer shell, through which sleeves 7 are passed for supplying concrete mixture 8 and depth vibrators 9.

 A sample 10 is installed next to the metal structure of the container body, which is structurally identical to the container sector and, in terms of plan, represents, for example, 1/4 or 1/8 of the container. The container and the sample sector are the same in height. A feature is the performance of the shell shell sample, which allows you to use them repeatedly. In the bottom 11 of the outer shell of the sample, as well as in the bottom 12 of the container body, holes "a" are made through which the sleeves 7 for supplying the concrete mixture 8 and the depth vibrators 9 are passed.

 The metal structures of the container and the sample sector are verified on the technological supports, after which the sleeves and depth vibrators are lowered through the holes in the bottoms of the outer shells of the container and the sample. Moreover, the mentioned sleeves and vibrators are equally uniformly distributed over the cross section of the container and the sample.

 In the installation zone of the container and the sample, a switchgear (hopper) 13 suspended on a crane suspension (not shown) is lowered, after which the flanges 14 of the sleeves 7 are connected to the corresponding flanges 15 of the switchgear 13. At the same time, deep vibrators 9 on the cable suspension are connected to the switchgear 16. On the switchgear for each sleeve has its own dispenser-switch 17, designed to control the flow of concrete mix 8.

 After loading the concrete mixture into the distribution device 13, the dispensers 17 are opened and the concrete mixture is simultaneously fed into the corresponding cavities between the shells of the container 1 and sample 10 with its simultaneous compaction by means of vibrators 9.

 As the concrete mixes fill the cavities of the container and the sample, the switchgear with the sleeves and vibrators attached to it is lifted up. The appearance of concrete mixture in the area of the upper sheet of the bottom 12 of the outer shell of the container body and the corresponding bottom 11 of the sample indicates the end of concreting. After closing the dispensers 17 and turning off the vibrators 9, the switchgear 13 is moved away from the concrete container, where the sleeves and vibrators are dismantled and washed and prepared for subsequent work.

 After concreting, the holes “a” in the bottoms of the container and sample bodies are closed with plugs 18 by welding.

To compensate for possible shrinkage of the concrete mixture after welding the plugs 18 through the holes in the latter, a control injection of the cement-sand mixture from mortar pumps (not shown) is performed under pressure up to 4 kgf / cm ² . After that, said holes are brewed.

 In the process of concreting, the amount of concrete mixture consumed and its quality are controlled. After concreting and the required exposure of the concrete mixture, demountable detachable shells of the sample are removed.

 After that, a sample is used to evaluate the quality of concrete filling by the height of the container and assess the physical and mechanical properties of the latter.

 Thus, the proposed method of manufacturing a container for SNF provides an increase in the reliability of the characteristics of the concrete filling of the container, as well as the possibility of confirming the physicomechanical properties of the concrete aggregate anywhere along the height of the container using samples taken from a sector sample without violating the integrity of the container itself.

Claims (2)

 1. A method of manufacturing a container for transporting and / or storage of spent nuclear fuel, comprising concreting a cavity between the metal outer and inner cylindrical shells with bottoms, characterized in that, in parallel with concreting the cavity of the container, concreting the cavity of the sample is identical to the sector of said container, wherein the seal concrete mixture in both of these cavities is carried out in the same mode, and after concreting, the sample shells are connected and n he is assessed for the quality of concrete filling by the height of the container and the assessment of the physico-mechanical properties of the latter.  2. The method according to claim 1, characterized in that when concreting the cavities of the container and the sample, the concrete mixture is supplied from a common switchgear.

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